In the practice, in particular in commercial vehicles, windshield wiper systems, which comprise a wiper arm with a wiper rod to the free end of which a so-called link cap for the oscillating connection with the carrier shaft or carrier yoke of a wiper blade is fastened have been used for some time, the link cap mostly being a bent sheet metal with an essentially U-shaped cross-section. Two side walls extend from a back into the direction of the windshield to be cleaned, and in the side walls there are aligning borings. The carrier shaft of the wiper blade to be connected with the wiper arm also has a U-shaped cross-section with a closed back and two parallel side cheeks projecting from the back into the direction of the windshield to be cleaned. In the side cheeks of the carrier shaft there are also borings aligning with one another. When mounted, the link cap engages into the carrier shaft of the wiper blade from the top in such a manner that the aligning borings of the link cap and the carrier shaft are arranged coaxially.
A pivot shaft is guided through the borings and secured axially. For axial securing, the pivot shaft comprises at one end a screw head and at the opposite end a thread, onto which a matching fastening nut is screwed. It has been shown to be advantageous that a relatively thin plastic part with a likewise U-shaped cross-section is arranged between the carrier shaft and the link cap and is used for minimizing a lateral play between the Carrier shaft and the link cap.
A disadvantage of this known connection is that the pivot shaft consists of heat treated steel to avoid early wear and that a wiper blade with an especially designed carrier shaft is necessary for coupling to the link cap.
A wiper arm of the type described at the beginning is also known from DE 34 23 416 A1. In this case, the link cap additionally has between its side walls a rip projecting downward from the back which is supported above the pivot shaft on the back of the carrier shaft. This rip lies between two projections extending upward from the carrier shaft back.
A further disadvantage of the two described solutions is that for changing the wiper blade the screw connection of the pivot shaft must be disconnected and then reconnected. This handling is quite complicated and requires the use of tools. Furthermore, it is not possible to connect a wiper blade of the otherwise common type, in which the carrier shaft has a fastening bolt in its connecting section, which is open at the top, between the parallel side cheeks with the link cap wiper arm. Therefore a number of styles of wiper blades.
An object of the invention is to develop a cost-effective connection piece which can be handled easily and which provides the possibility for simplifying the varieties with relation to types of wiper blades.
The advantage of the present invention is that, when using the connection piece of the invention, existing windshield wiper systems can be completed with a link cap wiper arm without any change with a wiper blade of the general type, i.e. with a fastening bolt between the parallel side cheeks of the carrier shaft, which is open in this area.
Because this connection piece, as it is generally done today, can be manufactured as a one-piece plastics part, this is particularly cost-effective.
The connection piece of the invention is preferably inserted with its upper connection part between the side walls of the link cap with a positive fit and fastened to the link cap by a screw projecting through the aligning borings in the side walls of the link cap and the hole through in its upper fastening part and axially secured by a nut. Because this fastening screw is not subject to any bearing movements, it can be made of cost-effective material which is not heat treated. Placing a thin plastic form part between the link cap and the upper fastening part of the connection piece is not necessary.
Because the bottom fastening part of the connection piece is provided with an easy to handle locking connection for locking onto the fastening bolt of the carrier shaft, the connection piece can be fastened to the link cap for a very long time. Changing the connection piece is only necessary after very frequent wiper blade change, when because of certain wear and tear a secure locking of the carrier shaft onto the connection piece is no longer guaranteed or, because of a too large lateral play between the side walls of the bottom fastening part and the side cheeks of the carrier shaft, a sufficient lateral guide of the wiper blade is no longer guaranteed. Exchanging the wiper blade is extremely easy and can be carried out without the help of additional tools. The wiper blade can be disconnected from the connection piece by merely applying corresponding force. In the same manner, the new wiper blade is connected with the connection piece in the opposite direction by the same force. For this, the carrier shaft of the wiper blade is placed on the bottom connection part of the connection piece from the bottom until the side walls of the bottom connection part reach between the side cheeks of the carrier shaft and, furthermore, the fastening bolt reaches into the stop notch, which is open at the bottom. With corresponding force, the carrier shaft is moved further into the direction of the link cap until it takes its final position in the stop notch and the same locks in at the circumference of the fastening bolt.
The connection piece or its upper connection part is preferably only as large as is absolutely necessary for a secure and form-stable connection with the link cap of the wiper arm. By pulling the exterior surfaces of the upper connection inwardly, the connection between the upper connection part of the connection piece and the link cap can be designed even more secure. Simultaneously, it provides for a harmonious exterior, which also has a positive effect on the wind flow conditions with regard to the wiper unit.
When, according to another advantageous formation the upper connection part is essentially hollow and is formed by corresponding outer walls as well as partitioning walls or stabilizing walls, material is saved, which has a favorable effect on the costs for the manufacture of the connection piece.
For a simple, but secure connection of the wiper blade with the connection piece, which furthermore guarantees the corresponding oscillation of the wiper blade with regard to the wiper arm or the connection piece, a stop notch, which is open at the bottom, for the fastening bolt of the carrier shaft is formed by two stop springs, which are arranged between the side walls of the bottom connection part and extend downward starting from a partitioning wall. Furthermore, in the area of the stop notch formed into the stop springs there are recesses, which are open downward at their edges in the side walls of the bottom connection part. When, furthermore, the upper edges of the recesses in the side walls are formed in such a manner that they at least at certain sections lie on the fastening bolt of the carrier shaft, the stability of the lock connection is improved even more. The danger that the fastening bolt of the carrier shaft may tilt during the opposite wiper movements in the lock connection is reduced more by this measure.
According to a further embodiment, the stop notch of the bottom connection part and the hole through of the upper connection part are arranged in a common plane, preferably in the vertical transverse center plane of the connection piece, therefore the conditions for the transfer of force from the wiper arm into the connection piece on the carrier shaft of the wiper blade are favorable. Furthermore, this measure is a basis for the generation of a symmetry of the connection piece, which is further cost-effective for the manufacture of the connection piece. This advantage is even more intensified when the connection piece is also symmetrical with relation to its vertical longitudinal center plane.
A further advantage is a formation according to which between the side walls of the bottom connection part stabilizing walls are arranged. This means that the bottom connection part is also essentially hollow; therefore, the connection piece can be manufactured with a minimum of material expenditure.
To guarantee a good lateral guide of the carrier shaft at the side walls of the bottom connection part and, therefore, balance a default play between the side walls of the bottom connection part and the side cheeks of the carrier shaft, it is recommended to provide the side walls of the bottom connection part with laterally projecting guide beads or with laterally projecting elastic sections.